I. Field of the Invention
The present invention relates generally to machines and, more particularly, to a machine to selectively position work members, such as a die set, at a work station in the machine.
II. Description of the Prior Art
There are many different types of machines in which a work member is positioned at a work station. For example, if the machine is a stamping press, the work member comprises a die set which is positioned at the work station. The dies in the die set are movable between an open position, in which the dies are spaced apart from each other, and a closed position, in which the dies press against each other to form the desired parts therebetween.
In many stamping presses, the stamping press is used to form a single part. In this case, the dies are positioned at a work station in the press and secured to the press in any conventional fashion. Actuation of the press then causes the stamping dies to move between their open and closed positions during the stamping operation.
While these previously known stamping presses have proven satisfactory where only a single type of part is produced by the press, in many different situations, it is necessary to change the dies at the work station in order to stamp different types of parts. Furthermore, in a production facility, the cycle time for the stamped parts forms a critical part of the overall manufacturing operation. Consequently, where it is necessary to change the dies in the press in order to stamp different types of parts, it is desirable that the time necessary to change the dies at the work station be as short as possible.
There have been previously known stamping presses in which one die set is positioned on one side of the press work station while, similarly, a second die set is positioned on the opposite side of the press work station. Each pair of dies in each die set forms a single type of part during operation of the press.
In order to selectively move one of the die pairs into the work station, it has been the previous practice to provide a conveyor section on each side of the press work station wherein each conveyor section supports one die set. A pusher is then associated with each die set in order to selectively move its associated die set between a standby position in which the die set is positioned away from the work station, and an operable position in which the die set is positioned at the work station. Conventional clamping means are then used to secure the die set at the work station to move the dies at the work station between an open and closed position.
While these previously known stamping presses with two die sets have proven successful in operation, in some situations three or even four different die sets are required to be used and rapidly changed in a single stamping press. The previously known presses have been unable to accommodate more than two die sets.